641—154.75(124E) Quality control. The laboratory shall have quality control protocols that include the following elements:
	154.75(1) Quality control samples required.
	a. 	The laboratory shall run quality control samples with every analytical batch of samples for chemical and microbiological analysis.
	b. 	For microbiological analysis, the laboratory shall develop procedures for quality control requirements for each analytical batch of samples.
	c. 	The laboratory shall analyze the quality control samples in exactly the same manner as the test samples to validate the laboratory testing results.
	154.75(2) Types of quality control samples. At a minimum, a laboratory shall have the following quality control samples as part of every analytical batch tested for chemical analytes:
	a. 	Negative control (method blank). A laboratory shall prepare and run at least one method blank sample with an analytical batch of 10 to 20 samples along with and under the same conditions, including all sample preparation steps, as the other samples in the analytical batch, to demonstrate that the analytical process did not introduce contamination.
	b. 	Positive control (laboratory control sample). A laboratory shall prepare and run at least one laboratory control sample with an analytical batch of 10 to 20 samples along with and under the same conditions, including all sample preparation steps, as the other samples in the analytical batch.
	c. 	Matrix spike sample. A laboratory shall prepare and run one or more matrix spike samples for each analytical batch.
	(1)	A laboratory shall calculate the percent recovery for quantitative chemical analysis by dividing the sample result by the expected result and multiplying that by 100. All quality control measures shall be assessed and evaluated on an ongoing basis, and quality control acceptance criteria shall be used. When necessary, the department may establish acceptance criteria on the department’s website (www.idph.iowa.gov).
	(2)	If quality control acceptance criteria are not acceptable, a laboratory shall investigate the cause, correct the problem, and rerun the analytical batch of samples. If the problem persists, the laboratory shall reprepare the samples and run the analysis again, if possible.
	d. 	Field duplicate sample. A laboratory shall prepare and run a duplicate sample as described in the laboratory testing requirements and acceptance criteria document in subrule 154.69(1). The acceptance criterion between the primary sample and the duplicate sample is less than or equal to 20 percent relative percent difference.
	154.75(3) Certified reference material for chemical analysis. The laboratory shall use a reference material for each analytical batch in accordance with the following standards:
	a. 	The reference material should be certified and obtained from an outside source, if possible. If a reference material is not available from an outside source, the laboratory shall make its own in-house reference material.
	b. 	Reference material made in-house should be made from a different source of standards than the source from which the calibration standards are made.
	c. 	The test result for the reference material shall fall within the quality control acceptance criteria. If it does not, the laboratory shall document and correct the problem and run the analytical batch again.
	154.75(4) Calibration standards. The laboratory shall prepare calibration standards by serially diluting a standard solution to produce working standards used for calibration of an instrument and quantitation of analyses in samples.
	154.75(5) Quality control-sample report. A laboratory shall generate a quality control-sample report that includes quality control parameters and measurements, analysis date, and type of matrix.
	154.75(6) Limit-of-detection and limit-of-quantitation calculations. For chemical method analysis, a laboratory shall calculate the limit of detection and limit of quantitation using generally accepted methodology.
[ARC 3836C, IAB 6/6/18, effective 7/11/18; ARC 4489C, IAB 6/5/19, effective 7/10/19]